Machine learning techniques for selecting paths in multi-vendor reconfigurable optical add/drop multiplexer networks

ABSTRACT

Devices, computer-readable media and methods are disclosed for selecting paths in reconfigurable optical add/drop multiplexer (ROADM) networks using machine learning. In one example, a method includes defining a feature set for a proposed path through a wavelength division multiplexing network, wherein the proposed path traverses at least one link in the network, and wherein the at least one link connects a pair of reconfigurable optical add/drop multiplexers, predicting an optical performance of the proposed path, wherein the predicting employs a machine learning model that takes the feature set as an input and outputs a metric that quantifies predicted optical performance, and determining whether to deploy a new wavelength on the proposed path based on the predicted optical performance of the proposed path.

This application is a continuation of U.S. patent application Ser. No.16/902,197, filed Jun. 15, 2020, now U.S. Pat. No. 11,038,616, which isa continuation of U.S. patent application Ser. No. 16/135,844, filedSep. 19, 2018, now U.S. Pat. No. 10,686,544, all of which are hereinincorporated by reference in their entirety.

The present disclosure relates generally to telecommunication networkoperations, e.g., in a wavelength division multiplexing (WDM) network,and more particularly to devices, computer-readable media, and methodsfor selecting paths in multi-vendor reconfigurable optical add/dropmultiplexer networks using machine learning.

BACKGROUND

Reconfigurable optical add/drop multiplexers (ROADMs) are increasinglybeing used in dense-wavelength-division-multiplexed (DWDM) networks tosupport Layer 1 services, such as private lines. Software-controlledROADMs manage data traveling over high-capacity fiber optic lines andcan automatically detect and adjust bandwidth, move traffic to differentlanes, turn off wavelengths for a variety of different reasons, and soforth.

Generally, each ROADM is connected to one or more other ROADMs by one ormore optical fiber pairs. A given ROADM will transmit an optical signalon one fiber in a pair and receive a return signal on the other fiber inthe pair; thus, each optical fiber transmits in a single direction. ALayer 1 service, or a wavelength, can then be set up between twotransponders, where each transponder is connected to a nearby ROADM. Thewavelength may then be routed through the ROADM network.

SUMMARY

Devices, computer-readable media and methods are disclosed for selectingpaths in reconfigurable optical add/drop multiplexer (ROADM) networksusing machine learning. In one example, a method includes defining afeature set for a proposed path through a wavelength divisionmultiplexing network, wherein the proposed path traverses at least onelink in the network, and wherein the at least one link connects a pairof reconfigurable optical add/drop multiplexers, predicting an opticalperformance of the proposed path, wherein the predicting employs amachine learning model that takes the feature set as an input andoutputs a metric that quantifies predicted optical performance, anddetermining whether to deploy a new wavelength on the proposed pathbased on the predicted optical performance of the proposed path.

In another example, a non-transitory computer-readable medium storesinstructions which, when executed by a processing system including atleast one processor, cause the processing system to perform operations.The operations include defining a feature set for a proposed paththrough a wavelength division multiplexing network, wherein the proposedpath traverses at least one link in the network, and wherein the atleast one link connects a pair of reconfigurable optical add/dropmultiplexers, predicting an optical performance of the proposed path,wherein the predicting employs a machine learning model that takes thefeature set as an input and outputs a metric that quantifies predictedoptical performance; and determining whether to deploy a new wavelengthon the proposed path based on the predicted optical performance of theproposed path.

In another example, a system includes a processor and a non-transitorycomputer-readable medium storing instructions which, when executed bythe processor, cause the processor to perform operations. The operationsinclude defining a feature set for a proposed path through a wavelengthdivision multiplexing network, wherein the proposed path traverses atleast one link in the network, and wherein the at least one linkconnects a pair of reconfigurable optical add/drop multiplexers,predicting an optical performance of the proposed path, wherein thepredicting employs a machine learning model that takes the feature setas an input and outputs a metric that quantifies predicted opticalperformance; and determining whether to deploy a new wavelength on theproposed path based on the predicted optical performance of the proposedpath.

BRIEF DESCRIPTION OF THE DRAWINGS

The teaching of the present disclosure can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an example system related to the present disclosure;

FIG. 2 illustrates various concepts related to the present disclosure;

FIG. 3 illustrates a flowchart of an example method for training amachine learning model to predict the optical performance of a proposedwavelength in a ROADM network;

FIG. 4 illustrates a flowchart of an example method for selectingoptical network paths in real-time using machine learning and

FIG. 5 illustrates an example high-level block diagram of a computerspecifically programmed to perform the steps, functions, blocks, and/oroperations described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The present disclosure broadly discloses devices, computer-readablemedia and methods for selecting paths in reconfigurable optical add/dropmultiplexer (ROADM) networks using machine learning. As discussed above,software-controlled ROADMs manage data traveling over high-capacityfiber optic lines and can automatically detect and adjust bandwidth,move traffic to different lanes, turn off wavelengths for a variety ofdifferent reasons, and so forth. Generally, each ROADM is connected toone or more other ROADMs by one or more optical fiber pairs. A givenROADM will transmit an optical signal on one fiber in a pair and receivea return signal on the other fiber in the pair; thus, each optical fibertransmits in a single direction. A Layer 1 service, or a wavelength, canthen be set up between two transponders, where each transponder isconnected to a nearby ROADM. The wavelength may then be routed throughthe ROADM network.

Various factors can affect the quality of an optical signal beingtransmitted over a wavelength in a ROADM network. For instance,imperfections in the optical fibers can add noise, and signaldistortions may be introduced as the optical signal passes throughequipment (e.g., ROADMs and amplifiers) and over distance. Thus, beforeprovisioning a new wavelength, the new wavelength may first be evaluatedby the service provider to verify that the new wavelength satisfies theservice provider's optical performance standards (e.g., meets a targetor threshold bit error rate (BER)). In some cases, the best optical pathmay not necessarily be the shortest one (due, e.g., to various networkconditions, imperfections in the optical fibers, etc.). Conventionally,evaluation of proposed wavelengths is based on detailed knowledge ofvendor equipment and is performed using vendor-specific tools that useproprietary software. Thus, although this conventional approach may beeffective for single-vendor networks (i.e., networks in which a singlevendor provides all of the equipment), it is infeasible for multi-vendornetworks (i.e., networks in which multiple vendors may provide theequipment).

In one example, the present disclosure relates to a ROADM-based networkaccording to an open standard, such as the Open ROADM Multi-SourceAgreement. Unlike ROADMs that are vendor specific and highlyproprietary, and which may require custom and static configuration andprovisioning, open standard ROADMs and optical plug-ins allowmulti-vendor interoperability where various equipment supportstandardized application programming interfaces (APIs). Examples of thepresent disclosure use machine learning techniques to predict theoptical performance (e.g., as quantified, for example, by the bit errorrate) of new wavelengths in Open ROADM-based networks. In one example,the prediction is based on the characteristics and optical performanceof existing wavelengths in the network, and requires little or noknowledge of the internal configuration of the network equipment. Theseand other aspects of the present disclosure are discussed in greaterdetail below in connection with the examples of FIGS. 1-5. Althoughexamples of the present disclosure are discussed within the context ofmulti-vendor networks such as Open ROADM-based networks, these examplesmay apply to single-vendor networks as well.

To aid in understanding the present disclosure, FIG. 1 illustrates anexample system 100 comprising a plurality of different networks in whichexamples of the present disclosure for selecting paths in ROADM networksmay operate. The overall communications system 100 may include anynumber of interconnected networks which may use the same or differentcommunication technologies. As illustrated in FIG. 1, system 100 mayinclude a network 105, e.g., a core telecommunication network. In oneexample, the network 105 may comprise a backbone network, or transportnetwork, such as an Internet Protocol (IP)/Multi-Protocol LabelSwitching (MPLS) network, where label switched paths (LSPs) can beassigned for routing Transmission Control Protocol (TCP)/IP packets,User Datagram Protocol (UDP)/IP packets, and other types of protocoldata units (PDUs) (broadly “traffic”). However, it will be appreciatedthat the present disclosure is equally applicable to other types of dataunits and network protocols. For instance, the network 105 may utilizeIP routing (e.g., without MPLS). Furthermore, network 105 may comprisemultiple networks utilizing different protocols, all utilizing a sharedunderlying WDM infrastructure (fibers, amplifiers, ROADMs, etc.), e.g.,an optical transport network. In this regard, it should be noted that asreferred to herein, “traffic” may comprise all or a portion of atransmission, e.g., a sequence or flow, comprising one or more packets,segments, datagrams, frames, cells, PDUs, service data units, bursts,and so forth. The particular terminology or types of data units involvedmay vary depending upon the underlying network technology. Thus, theterm “traffic” is intended to refer to any quantity of data to be sentfrom a source to a destination through one or more networks.

In one example, the network 105 may be in communication with networks160 and networks 170. Networks 160 and 170 may comprise wirelessnetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11/Wi-Fi networks and the like), cellular access networks (e.g.,Universal Terrestrial Radio Access Networks (UTRANs) or evolved UTRANs(eUTRANs), and the like), circuit switched networks (e.g., publicswitched telephone networks (PSTNs)), cable networks, digital subscriberline (DSL) networks, metropolitan area networks (MANs), Internet serviceprovider (ISP) networks, peer networks, and the like. In one example,the networks 160 and 170 may include different types of networks. Inanother example, the networks 160 and 170 may be the same type ofnetwork. The networks 160 and 170 may be controlled or operated by asame entity as that of network 105 or may be controlled or operated byone or more different entities. In one example, the networks 160 and 170may comprise separate domains, e.g., separate routing domains ascompared to the network 105. In one example, networks 160 and/ornetworks 170 may represent the Internet in general.

In one example, network 105 may transport traffic to and from userdevices 141 and 142. For instance, the traffic may relate tocommunications such as voice telephone calls, video and othermultimedia, text messaging, emails, and so forth between the userdevices 141 and 142, or between the user devices 141 and/or 142 andother devices that may be accessible via networks 160 and 170. Userdevices 141 and 142 may comprise, for example, cellular telephones,smart phones, personal computers, other wireless and wired computingdevices, private branch exchanges, customer edge (CE) routers, mediaterminal adapters, cable boxes, home gateways and/or routers, and soforth.

As stated above, network 105 comprises a WDM network (e.g., a densewavelength division multiplexing (DWDM) network). Accordingly, in oneexample, the nodes 131-137 may include optical components, such asROADMs, and the links between nodes 131-137 may comprise fiber opticcables. For ease of illustration, a portion of the links is specificallylabeled as links 120-129. Inset 101 illustrates a portion of the network105 comprising nodes 136 and 137, and links 125-129. As shown in inset101, node 136 includes a ROADM 191 coupled to links 125, 126, and 128, aplurality of add/drop ports 194, and a network switch 193 coupled to theROADM 191 via one of the plurality of add/drop ports 194 and atransponder 192. It should be noted that the network switch 193 mayinclude a transceiver 199 which is coupled to the transponder 192 via afiber optic patch cord 171. The transponder 192 may include a clientside transceiver 174 (which in one example may comprise the same orsimilar quality optics as the transceiver 199, e.g., an SFP transceiver,a 10 Gb small form factor pluggable (XFP) transceiver, or the like) anda ROADM side/line side transceiver 175 (which may comprise higherquality optics for transmitting and receiving signals over longerdistances between nodes of the network 105, e.g., hundreds of kilometersup to 2,000 or more kilometers) coupled to one of the add/drop ports 194via a fiber optic patch cord 172. In one example, the transceiver 192may comprise a muxponder that may aggregate several lower bandwidthsignals from network switch 193 and/or from one or more other networkswitches, routers, or other client devices at node 136 into a combinedsignal for transmission over one of the network links 125, 126, or 128.

Similarly, node 137 includes a ROADM 195 coupled to links 126, 127, and129, a plurality of add/drop ports 198, and a network switch 197 coupledto ROADM 195 via a patch cord 173 between one of the plurality ofadd/drop ports 198 and a transponder 196. It should be noted that asillustrated in FIG. 1, the transponder 196 may be integrated withinnetwork switch 197, e.g., within a pluggable slot (such as a CFP or CFP2slot, a QSFP28 slot, or the like). In one example, transponder 196 maybe capable of transmitting and/or receiving optical signals for use inmetro or transport applications at data rates of 100 Gb/s or greater.However, in another example, transponder 196 may transmit and receive atlower data rates, such as 25 Gb/s, 10 Gb/s etc. ROADMs 191 and 195 maycomprise colorless ROADMs, directionless ROADMs, colorless anddirectionless ROADMs (CD ROADMs), contentionless ROADMs, e.g.,colorless, directionless, and contentionless (CDC) ROADMs, and so forth.Additionally, it should be noted that these ROADMs may include OpenROADMs with open standards allowing interoperability of different ROADMsmanufactured by different vendors.

It should be noted that in each of nodes 136 and 137, any number ofrouters, switches, application servers, and the like may be connected toone of the plurality of add/drop ports 194 or plurality of add/dropports 198, e.g., via additional transponders and/or transceivers. Inaddition, in other examples, additional components, such as additionalROADMs, may be connected to one of the plurality of add/drop ports 194or plurality of add/drop ports 198. For instance, in another example,node 137 may include a number of ROADMs, wavelength selective switches(WSSs), and other components that are interconnected to provide a higherdegree node. In addition, as referred to herein the terms “switch” and“network switch” may refer to any of a number of similar devices, e.g.,including: a layer 2 switch (e.g., an Ethernet switch), a layer 3switch/multi-layer switch, a router (e.g., a router which may alsoinclude switching functions), or the like. It should also be noted thatnodes 131-135 may have a same or similar setup as nodes 136 and 137. Inaddition, in one example, any one or more of components 181-184 may alsocomprise an optical node with a same or similar setup as nodes 136 and137.

As further illustrated in FIG. 1, network 105 includes a softwaredefined network (SDN) controller 155 and a path computation element(PCE) 150. In one example, the SDN controller 155 may comprise acomputing system or server, such as computing system 500 depicted inFIG. 5, and may be configured to provide one or more operations orfunctions for selecting paths in ROADM networks using machine learning.In addition, it should be noted that as used herein, the terms“configure,” and “reconfigure” may refer to programming or loading aprocessing system with computer-readable/computer-executableinstructions, code, and/or programs, e.g., in a distributed ornon-distributed memory, which when executed by a processor, orprocessors, of the processing system within a same device or withindistributed devices, may cause the processing system to perform variousfunctions. Such terms may also encompass providing variables, datavalues, tables, objects, or other data structures or the like which maycause a processing system executing computer-readable instructions,code, and/or programs to function differently depending upon the valuesof the variables or other data structures that are provided. As referredto herein a “processing system” may comprise a computing deviceincluding one or more processors, or cores (e.g., a computing system asillustrated in FIG. 5 and discussed below) or multiple computing devicescollectively configured to perform various steps, functions, and/oroperations in accordance with the present disclosure. In addition, withrespect to ROADMs, “configured” and “reconfigured” may refer toinstructions to adjust a WSS to route different wavelengths to differentfibers/links and/or to different add/drop ports. With respect to networkswitches and transponders, “configured” and “reconfigured” may refer toinstructions to send or receive at a particular bitrate, to utilize aparticular transmit power, to transmit or receive on a particularwavelength, and the like.

In one example, nodes 131-137 and components 181-184 (and/or the devicestherein) may be controlled and managed by SDN controller 155. Forinstance, in one example, SDN controller 155 is responsible for suchfunctions as provisioning and releasing instantiations of VNFs toperform the functions of routers, switches, and other devices,provisioning routing tables and other operating parameters for the VNFs,and so forth. Thus, various components of network 105 may comprisevirtual network functions (VNFs) which may physically comprise hardwareexecuting computer-readable/computer-executable instructions, code,and/or programs to perform various functions. For example, the functionsof SDN controller 155 may include the selection of a network functionvirtualization infrastructure (NFVI) from among various NFVIs availableat nodes 131-137 in network 105 to host various devices, such asrouters, gateways, switches, route reflectors, firewalls, media servers,and so forth. To illustrate, network switches 193 and 197 may physicallyreside on host devices that may be configured to be a firewall, a mediaserver, a network switch, a router, and so forth.

In addition, SDN controller 155 may also manage the operations ofoptical components of the network 105. For instance, SDN controller 155may configure paths for wavelength connections via the network 105 byconfiguring and reconfiguring ROADMs at nodes 131-137 and components181-184. For example, SDN controller 155 may provide instructions tocontrol wavelength selective switches (WSSs) within the ROADMs, as wellas transceivers and/or transponders connected to the ROADM add/dropports. In one example, SDN controller 155 may maintain communicationswith nodes 131-137 and components 181-184 (and/or the devices therein)via a number of control links 151 which may comprise secure tunnels forsignaling communications over an underling IP infrastructure of network105, e.g., including fibers/links 120-129, etc. In other words, thecontrol links 151 may comprise virtual links multiplexed withtransmission traffic and other data traversing network 105 and carriedover a shared set of physical links. Alternatively, or in addition, thecontrol links 151 may comprise out-of-band links, e.g., optical ornon-optical connections that are different from fibers/links 120-129. Inone example, SDN controller 155 may be in communication with nodecontrollers at each node 131-137 (and in one example at components181-184). For example, node controllers 178 and 179 may be responsiblefor instantiating and releasing instances of virtual machines at nodes136 and 137 respectively, and for configuring and reconfiguringoperations of associated ROADMs, such as ROADMs 191 and 195,transponders 192 and 196, transceiver 199, network switches 193 and 197,and so on. Thus, in one example, node controllers 178 and 179 mayreceive instructions for configuring and reconfiguring ROADMs 191 and195 from SDN controller 155, e.g., via control links 151. Alternatively,or in addition, control links 151 may provide connections between SDNcontroller 155 and ROADMs 191 and 195, transponders 192 and 196,transceiver 199, and network switches 193 and 197 without theinvolvement of separate node controllers 178 and 179. In one example,the SDN controller 155 may also comprise a virtual machine operating onone or more NFVI/host devices, or may comprise one or more dedicateddevices. For instance, SDN controller 155 may be collocated with one ormore VNFs, may be deployed in one or more different host devices, or ata different physical location or locations, and so forth.

In addition, in one example, SDN controller 155 may represent aprocessing system comprising a plurality of controllers, e.g., amulti-layer SDN controller, one or more federated layer 0/physical layerSDN controllers, and so forth. For instance, a multi-layer SDNcontroller may be responsible for instantiating, tearing down,configuring, reconfiguring, and/or managing layer 2 and/or layer 3 VNFs(e.g., a network switch, a layer 3 switch and/or a router, etc.),whereas one or more layer 0 SDN controllers may be responsible foractivating and deactivating optical networking components, forconfiguring and reconfiguring the optical networking components (e.g.,to provide circuits/wavelength connections between various nodes or tobe placed in idle mode), for receiving management and configurationinformation from such devices, for instructing optical devices atvarious nodes to provision optical network paths in accordance with thepresent disclosure, and so forth. In one example, the layer 0 SDNcontroller(s) may in turn be controlled by the multi-layer SDNcontroller. For instance, each layer 0 SDN controller may be assigned tonodes/optical components within a portion of the network 105. Inaddition, these various components may be co-located or distributedamong a plurality of different dedicated computing devices or sharedcomputing devices (e.g., NFVI) as described herein.

As further illustrated in FIG. 1, the network 105 also includes a pathcomputation element (PCE) 150. In one example, PCE 150 may comprise acomputing system or server, such as computing system 500 depicted inFIG. 5, and may be configured to provide one or more operations orfunctions in accordance with the present disclosure. PCE 150 may becollocated with one or more of nodes 131-137, components 181-184, or SDNcontroller 155, or may be deployed at one or more different physicallocations. In one example, network 105 may comprise a distributed PCEenvironment with multiple PCEs responsible for different zones, e.g.,segregated by geographic area, by functionality type, etc. Thus, forexample, PCE 150 may be selected to manage path utilizations in theportion of network 105 relating to components 181-184 and nodes 131-137.For instance, the PCE 150 may be selected by the SDN controller 155.

As illustrated in FIG. 1, PCE 150 may be in communication with SDNcontroller 155 and may provide path computation decisions, such asreachability determinations, to the SDN controller 155. In turn, SDNcontroller 155 may provision wavelength connections via paths identifiedby PCE 150. For instance, SDN controller 155 may receive a request toestablish a wavelength connection from component 181 to component 184,e.g., to carry traffic between user devices 141 and 142. SDN controller155 may then forward the request to PCE 150 to calculate a path. Forillustrative purposes, PCE 150 may consider a candidate path comprisinglinks 120, 121, 122, 123, and 124, and may make a reachabilitydetermination as part of a path computation process. If the pathcomprising links 120, 121, 122, 123, and 124 is determined to be“reachable” and if the path satisfies other criteria, such as being aleast cost path, or a path that supports a least cost route as computedat a higher layer (e.g., for IP or IP/MPLS routing), the PCE 150 mayreturn the path to SDN controller 155 for deployment. SDN controller 155may then communicate with the nodes 131, 132, 133, and 135, andcomponents 181 and 184 to configure ROADMs to maintain a wavelengthconnection over the path. It should be noted that although nodes 131,132, 133, and 135 may include network switches and/or routers operatingin the non-optical domain, a wavelength connection via the pathcomprising links 120, 121, 122, 123, and 124 may be optically switchedthrough ROADMs at nodes 131, 132, 133, and 135 (and bypassing anyrouters (e.g., layer 3 routers) or non-optical switches) that may bepresent at the respective nodes. In one example, components 181 and 184may be configured to add and drop the wavelength of the wavelengthconnection and to perform optical-electrical conversion and vice versa,e.g., via a transponder coupled to an add/drop port of a ROADM therein.

In this regard, PCE 150 may store various data in connection withmanaging path utilizations for telecommunication network tunnels. Forinstance, PCE 150 may maintain a topology information block (TIB) thatincludes records for various links/fibers between the nodes 131-137 andcomponents 181-184 in network 105, such as the available wavelengths,the wavelengths assigned/in-use and/or the available/free wavelengths,the paths assigned to respective wavelengths, the fiber lengths,capacities, and ages, the availability of transponders, switches, and/orother infrastructure at various nodes, transponder and/or transceiverperformance capabilities of the various nodes, information regarding anyprotection scheme involving a fiber, and/or any particular wavelengthsthat may be utilized over the fiber, and so forth.

It should be noted that the system 100 has been simplified. In otherwords, the system 100 may be implemented in a different form than thatillustrated in FIG. 1. For example, the system 100 may be expanded toinclude additional networks and additional network elements (not shown)such as border elements, routers, switches, policy servers, securitydevices, gateways, a content distribution network (CDN) and the like,without altering the scope of the present disclosure. In addition,system 100 may be altered to omit various elements, substitute elementsfor devices that perform the same or similar functions and/or combineelements that are illustrated as separate devices. For example, SDNcontroller 155, PCE 150, and/or other network elements may comprisefunctions that are spread across several devices that operatecollectively as a SDN controller, a PCE, etc. In another example, PCE150 and SDN controller 155 may be integrated into a single device. Inanother example, PCE 150 may maintain its own connections to nodes131-137 and components 181-184 and may send instructions to variousdevices to configure paths for wavelength connections in accordance withthe present disclosure. In another example, nodes 131-137 and/orcomponents 181-184 may include fiber loss test sets (FLTSs), opticaltime domain reflectometers (OTDRs), polarization mode dispersion (PMD)measurement devices, and the like which may be used to measure fiberloss and PMD over various links.

In addition, the foregoing includes examples where operations forselecting optical network paths in real-time using machine learning areperformed by PCE 150, and/or by PCE 150 in conjunction with otherdevices under the control and instruction of SDN controller 155.However, in other, further, and different examples, aspects of selectingoptical network paths in real-time using machine learning may includetransponders and/or network switches performing one or more operationsautonomously. Thus, these and other modifications of the system 100 areall contemplated within the scope of the present disclosure.

FIG. 2 illustrates various concepts related to the present disclosure.In particular, FIG. 2 illustrates a portion of a ROADM network 200. Theportion of the ROADM network 200 comprises a plurality of ROADMs 202₁-202 _(n) (hereinafter individually referred to as a “ROADM 202” orcollectively referred to as “ROADMs 202”) connected by a plurality ofoptical fiber sections 204 ₁-204 _(m) (hereinafter individually referredto as an “optical fiber section 204” or collectively referred to as“optical fiber sections 204”). The ROADM network 200 may additionallycomprise at least one optical amplifier 206.

Moreover, at least one ROADM 202 may be coupled (e.g., via a pluralityof add/drop ports) to a transponder 208 ₁-208 _(p) (hereinafterindividually referred to as a “transponder 208” or collectively referredto as “transponders 208”). A ROADM 202 and a transponder 208 maycollectively form what may be referred to as an “office” 210 ₁-210 _(p)(hereinafter individually referred to as an “office 210” or collectivelyreferred to as “offices 210”). Each office 210 may be associated with aCommon Language Location Identifier (CLLI) code. Moreover, any office210 may include more than one ROADM 202 and may contain any or all ofthe equipment illustrated at nodes 136 and 137 of FIG. 1.

A connection or wavelength (an example of which is illustrated in FIG. 2at 216) may be formed between a pair of transponders 208 (or a pair ofoffices 210). A connection may be associated with a route identificationnumber (RIN). A connection between two ROADMs, including anyintermediary ROADMs, amplifiers, and fiber sections, may form a domain.

A project may refer to a construction project, e.g., where theconstruction project may comprise the augmentation of an existingnetwork. For example, a project might include the addition of new ROADMlinks, optical amplifiers, transponders, and/or ROADMs to an existingROADM network. Thus, the sequence of ROADMs 202 in FIG. 2 mightrepresent one project.

According to examples of the present disclosure, an optical wavelength212 may traverse one or more ROADM links (an example of which isillustrated in FIG. 2 at 214), i.e., connections between pairs of ROADMs202. Each ROADM link in turn may traverse one or more optical fibersections 204. Different optical fiber sections 204 may use differentfiber types (e.g., enhanced large effective area fiber (ELEAF),non-dispersion-shifted fiber (NDSF), TRUEWAVE CLASSIC (TWC) fiber,TRUEWAVE REDUCED SLOPE (TWRS) fiber, or the like); for instance, achange of fiber type is indicated in FIG. 2 at 218. A change in fibertype may occur even where there is no ROADM 202 or amplifier 206, asshown.

FIG. 3 illustrates a flowchart of an example method 300 for training amachine learning model to predict the optical performance of a proposedwavelength in a ROADM network. In one example, steps, functions and/oroperations of the method 300 may be performed by a network-based device,such as PCE 150 in FIG. 1, or any one or more components thereof, suchas a processing system. Alternatively, or in addition, the steps,functions and/or operations of the method 300 may be performed by aprocessing system collectively comprising a plurality of devices asillustrated in FIG. 1, such as PCE 150, SDN controller 155, ROADM 191and/or ROADM 195, transponders 192 and 196, and/or transceiver 199,network switches 193 and/or 197, node controllers 178 and/or 179, and soforth. In one example, the steps, functions, or operations of method 300may be performed by a computing device or system 500, and/or aprocessing system 502 as described in connection with FIG. 5 below. Forinstance, the computing device 500 may represent at least a portion of aPCE or an SDN controller, in accordance with the present disclosure. Forillustrative purposes, the method 300 is described in greater detailbelow in connection with an example performed by a processing system,such as processing system 502, or a processing system comprising aplurality of devices. The method 300 begins in step 302 and proceeds tostep 304.

At step 304, the processing system may collect training data from aROADM network. The ROADM network may be a single-vendor network (e.g.,including ROADMs supplied by a single vendor) or a multi-vendor network(e.g., including ROADMs supplied by at least two vendors, such as anOpen ROADM network). The training data may comprise optical datacollected over a fixed period of time (e.g., one day, two days, etc.) aswell as network data which may be less susceptible to fluctuation overtime. The network data can be used to interpret the optical data.

In one example, the optical data includes static fiber design data thatdoes not change appreciably from one time period to another (e.g., fiberpairs, sources, destinations, types, lengths, losses, margins,polarization mode dispersions, flags), measured fiber loss data forspecific time periods (e.g., port identifiers, node names, measuredlosses), ROADM and optical amplifier equipment details (e.g., nodenames, types, bays, domains, statuses), transponder wavelength designdata (e.g., locations, projects, systems, bays, shelves, slots, types),and bit error rate (BER) measurements (e.g., locations, ports, types,and bit error rates before forward error correction (preFEC BER)).

In one example, the network data includes project data (e.g., projectIDs, facility IDs, route IDs, sub-facilities), route data (e.g., routeIDs, end points, distances), route/span mapping data (e.g., route IDs,span IDs, sequences), location data (e.g., CLLI codes, latitudes,longitudes), and transport deployment plans (TDPs) (e.g., lists of ROADMsections by project).

At step 306, the processing system may correlate the training data togenerate feature sets for optical wavelengths in the ROADM network.Correlation of the training data may be complicated in some examples bythe manner in which the training data is defined. For instance, thetraining data may be defined in terms of projects, domains, RINs, officeCLLI codes, and/or the like.

In one example, correlation of the training data in step 306 includes atleast one of: matching amplifiers and ROADMs in the ROADM network tooptical fiber sections based on domain information; pairing transponderports in the ROADM network based on project and time, distance, place(TDP) data to form connections (wavelengths); mapping ROADM links tospan data; and mapping connections (wavelengths) to ROADM links based onRIN and span information. In one example, if a wavelength cannot bemapped (e.g., due to incomplete or ambiguous data), the wavelength isdiscarded from the training data.

In one example, correlation of training data in step 306 may discard (orat least aggregate) other types of training data. Because differentwavelengths may traverse different numbers of ROADM links and opticalfiber sections, it may not be possible to retain all of the trainingdata and still maintain an equal number of features per wavelength.Thus, for example, instead of including the measured loss for everyoptical fiber section along every wavelength (which would result in avariable number of features), the loss data may instead be summarized bya group of a fixed number of features (e.g., total fiber loss, largestloss value, second largest loss value, and average loss per opticalfiber section). However, it should be noted that some features (e.g.,optical signal to noise ratio (OSNR)) could potentially be calculatedbased on a variable number of optical fiber sections.

In one example, the feature set produced for each wavelength inaccordance with step 306 includes one or more of the following features:calculated OSNR (based on measured loss and optical fiber type); speed(e.g., 40 Gigabits per second or 100 Gigabits per second); slot numberon dense wavelength division multiplexing unit (DWDMU) facility (whichdetermines the wavelength's frequency); polarization mode dispersion(PMD); number of pass-through ROADMs; number of amplifiers in the path;length of path (e.g., in miles or other units); length (e.g., inkilometers or other units) of each optical fiber type (potentially withseparate totals for fiber junctions); measured fiber loss (total,largest, second largest, and average per mile or other unit); opticalreturn loss (ORL) (i.e., a measure of reflection as “good” or “bad”);margin, i.e., the difference between net power and minimum power (total,largest, and average per mile or other unit); and measurement date(e.g., month, year, etc.).

In a further example, the feature set may further include featuresrelated to interference from adjacent wavelengths. Each wavelength isassigned to a specific frequency (or “slot”) on an optical fiber pair.Wavelengths assigned to adjacent slots may interfere with each other.Thus, if known, the statuses of the adjacent slots on either side of awavelength (e.g., “in use” or “idle”) may provide information aboutinterference.

In step 308, the processing system may apply a machine learningalgorithm to the optical wavelength feature sets produced in step 306 tolearn, for each wavelength for which a feature set is available, theeffect of the features on the wavelength's performance (e.g., pre-FECBER in each direction). In one example, the BERs in the training datarange from 10⁻¹⁴ to 10⁻². In this case, the BER to be estimated by themachine learning algorithm is log₁₀(BER).

In one example, the machine learning algorithm is a penalized linearregression algorithm (e.g., ridge regression, least absolute shrinkageselection operator (LASSO), etc.). For instance, the machine learningalgorithm may estimate a coefficient β in a model of the type:

$\begin{matrix}{{{{{\min\limits_{\beta}{{y - {\beta\; x}}}_{2}^{2}} + {a{\beta }_{p}^{p}}},{with}}p = {{2\mspace{14mu}{for}\mspace{14mu}{ridge}\mspace{14mu}{regression}\mspace{14mu}{or}\mspace{14mu} p} = {1\mspace{14mu}{for}\mspace{14mu}{LASSO}}}},} & \left( {{EQN}.\mspace{11mu} 1} \right)\end{matrix}$

where X denotes the set of features for the wavelengths and y denotesthe measured output values (log₁₀(BER)). The LASSO example encouragessparsity in β (as would be expected if most of the features have noimpact on BER), while the ridge regression example reduces instabilityin estimating β when the features are highly correlated.

In another example, the machine learning algorithm is an ensemble ofregression trees (e.g., gradient boosted regression trees, randomforests, etc.). A regression tree is a piecewise linear regression thatiteratively splits the data according to an error criterion and fitsseparate regressions to each portion of the split data. Both gradientboosted regression trees and random forests train several differentregression trees over different subsets of the features, and take anaverage over all of the trees to obtain a final estimate.

In step 310, the processing system may output a machine learning modelthat is trained to output an estimated performance metric (e.g., pre-FECBER as (log₁₀(BER)) for an input wavelength, where the estimated BER isbased on a defined set of features (e.g., the features discussed inconnection with step 306) for the wavelength.

The method 300 may end in step 312.

It should be noted that the method 300 may be expanded to includeadditional steps or may be modified to include additional operationswith respect to the steps outlined above. For instance, in one example,the method 300 may be repeated as additional training data becomesavailable. Thus, these and other modifications are all contemplatedwithin the scope of the present disclosure.

A machine learning model trained according to the method 300 maytherefore be based on all available and current information aboutexisting and proposed wavelengths from a single vendor or a multi-vendor(e.g., Open ROADM) network, such as distance, bit rate, frequency, fibertypes, number of pass-through ROADMs, measured fiber loss, polarizationmode dispersion, and/or calculated optical signal to noise ratio. Themachine learning model may aggregate and integrate data from a variablenumber of optical fiber sections into a fixed number of machine learningmodel features.

Moreover, the machine learning model does not need to have access tovendors' proprietary information about the ROADMs and can work withROADMs from multiple vendors.

The machine learning model can predict, in real time, wavelengthperformance (e.g., pre-FEC BER) for proposed wavelengths based onperformance data from existing wavelengths, which realistically reflectsthe current network conditions. The prediction can also be made with farless data than is used by conventional machine learning applications.

The above-described approach allows for flexible implementation ofvarious machine learning techniques, including techniques in addition tothose explicitly discussed (e.g., penalized linear regression,multilayer perceptron, random forest trees, and yet-to-be-developedtechniques). A closed loop mechanism may allow the machine learningmodel parameters to be continuously updated, as described in furtherdetail below in connection with FIG. 4, as new data becomes availableand as the network evolves with new equipment and technologies.

FIG. 4 illustrates a flowchart of an example method 400 for selectingoptical network paths in real-time using machine learning. In oneexample, steps, functions and/or operations of the method 400 may beperformed by a network-based device, such as PCE 150 in FIG. 1, or anyone or more components thereof, such as a processing system.Alternatively, or in addition, the steps, functions and/or operations ofthe method 400 may be performed by a processing system collectivelycomprising a plurality of devices as illustrated in FIG. 1, such as PCE150, ROADM 191 and/or ROADM 195, transponders 192 and 196, and/ortransceiver 199, network switches 193 and/or 197, node controllers 178and/or 179, and so forth. In one example, the steps, functions, oroperations of method 400 may be performed by a computing device orsystem 500, and/or a processing system 502 as described in connectionwith FIG. 5 below. For instance, the computing device 500 may representat least a portion of a PCE or SDN controller, in accordance with thepresent disclosure. For illustrative purposes, the method 400 isdescribed in greater detail below in connection with an exampleperformed by a processing system, such as processing system 502, or aprocessing system comprising a plurality of devices. The method 400begins in step 402 and proceeds to step 404.

At step 404, the processing system may generate a proposed path for anew wavelength in a ROADM network. In one example, the proposed path isgenerated in response to a request for the new wavelength. The proposedpath may traverse one or more ROADM links in the ROADM network, as wellas one or more optical fiber sections (which may be of different fibertypes). The ROADM network may be a single-vendor network (e.g.,including ROADMs supplied by a single vendor) or a multi-vendor network(e.g., including ROADMs supplied by at least two vendors, such as anOpen ROADM network).

In step 406, the processing system may define a set of features for theproposed path. The set of features may include both optical data andnetwork data. For instance, the set of path features may include one ormore of: calculated OSNR (based on measured loss and optical fibertype); speed (e.g., 40 Gigabits per second or 100 Gigabits per second);slot number on dense wavelength division multiplexing unit (DWDMU)facility (which determines the wavelength's frequency); polarizationmode dispersion (PMD); number of pass-through ROADMs; number ofamplifiers in the path; length of path (e.g., in miles or other units);length (e.g., in kilometers or other units) of each optical fiber type(potentially with separate totals for fiber junctions); measured fiberloss (total, largest, second largest, and average per mile or otherunit); optical return loss (ORL) (i.e., a measure of reflection as“good” or “bad”); margin, i.e., the difference between net power andminimum power (total, largest, and average per mile or other unit); andmeasurement date (e.g., month, year, etc.).

In step 408, the processing system may predict the optical performanceof the proposed path based on the set of features, using a machinelearning model. In one example, the machine learning model has beentrained (e.g., in accordance with the method 300 described above) topredict optical performance based on a fixed set of path features. Forinstance, the machine learning model may be a penalized linearregression model or an ensemble of regression trees as discussed above.The predicted optical performance may be quantified as the proposedpath's estimated BER (e.g., pre-FEC BER) or as another performancemetric.

In step 410, the processing system may determine whether the predictedoptical performance of the proposed path meets the service provider'soptical performance standards (e.g., meets a target or threshold biterror rate (BER) or other performance metric).

If it is determined in step 410 that the predicted optical performanceof the proposed path meets the service provider's optical performancestandards, then the method 400 may proceed to step 412. In step 412, theprocessing system may deploy the requested wavelength (e.g., byassigning the requested wavelength to a specific frequency or “slot” onthe optical fiber pairs in the ROADM network).

Once the requested wavelength has been deployed, the method 400 mayproceed to step 414. In step 414, the processing system may collect dataregarding the performance of the new wavelength. The data may includeinformation about any of the features discussed in connection with step406.

In step 416, the processing system may perform further training of themachine learning model using the collected data regarding theperformance of the new wavelength. The further training may be performedin accordance with the method 300 described in connection with FIG. 3.This will help to refine the machine learning model and improve theaccuracy of the optical performance predictions that are made for futureproposed paths. It should be noted that the machine learning model maynot be retrained immediately following deployment of every newwavelength. For instance, further training of the machine learning modelin accordance with step 416 could be performed periodically (e.g.,according to some repeating, defined schedule), after collection of somethreshold amount of new data or deployment of a threshold number of newwavelengths, randomly, on-demand, or according to any other schedule.

The method 400 may end in step 418 after performing the further trainingof the machine learning model.

Referring back to step 410, if it instead is determined that thepredicted optical performance of the proposed path does not meet theservice provider's optical performance standards, then the method 400may return to step 404 and generate a new proposed path. The method 400may then proceed as described above to evaluate the optical performanceof the new proposed path. New proposed paths may be generated as manytimes as necessary until a proposed path is found that meets the serviceprovider's optical performance standards.

It should be noted that in addition to estimating the opticalperformance of proposed paths for new wavelengths, the machine learningmodel could also be used to evaluate the performance of existingwavelengths and to move the existing wavelengths to better performingalternative paths (e.g., as conditions in the ROADM network evolve).

Although not specifically specified, one or more steps, functions oroperations of the method 300 or the method 400 may include a storing,displaying, and/or outputting step as required for a particularapplication. In other words, any data, records, fields, and/orintermediate results discussed in the example method 300 or method 400can be stored, displayed, and/or outputted to another device as requiredfor a particular application. Furthermore, steps or blocks in FIG. 3 or4 that recite a determining operation or involve a decision do notnecessarily require that both branches of the determining operation bepracticed. In other words, one of the branches of the determiningoperation can be deemed as an optional step. In addition, one or moresteps, blocks, functions, or operations of the above described method300 or method 400 may comprise optional steps, or can be combined,separated, and/or performed in a different order from that describedabove, without departing from the examples of the present disclosure.

FIG. 5 depicts a high-level block diagram of a computing device orprocessing system specifically programmed to perform the functionsdescribed herein. As depicted in FIG. 5, the processing system 500comprises one or more hardware processor elements 502 (e.g., a centralprocessing unit (CPU), a microprocessor, or a multi-core processor), amemory 504 (e.g., random access memory (RAM) and/or read only memory(ROM)), a module 505 for selecting paths in ROADM networks using machinelearning, and various input/output devices 506 (e.g., storage devices,including but not limited to, a tape drive, a floppy drive, a hard diskdrive or a compact disk drive, a receiver, a transmitter, a speaker, adisplay, a speech synthesizer, an output port, an input port and a userinput device (such as a keyboard, a keypad, a mouse, a microphone andthe like)). In accordance with the present disclosure input/outputdevices 506 may also include antenna elements, transceivers, powerunits, and so forth. Although only one processor element is shown, itshould be noted that the computing device may employ a plurality ofprocessor elements. Furthermore, although only one computing device isshown in the figure, if the method 300 or method 400 as discussed aboveis implemented in a distributed or parallel manner for a particularillustrative example, i.e., the steps of the above method 300 or method400, or the entire method 300 or method 400 is implemented acrossmultiple or parallel computing devices, e.g., a processing system, thenthe computing device of this figure is intended to represent each ofthose multiple computing devices.

Furthermore, one or more hardware processors can be utilized insupporting a virtualized or shared computing environment. Thevirtualized computing environment may support one or more virtualmachines representing computers, servers, or other computing devices. Insuch virtualized virtual machines, hardware components such as hardwareprocessors and computer-readable storage devices may be virtualized orlogically represented. The hardware processor 502 can also be configuredor programmed to cause other devices to perform one or more operationsas discussed above. In other words, the hardware processor 502 may servethe function of a central controller directing other devices to performthe one or more operations as discussed above.

It should be noted that the present disclosure can be implemented insoftware and/or in a combination of software and hardware, e.g., usingapplication specific integrated circuits (ASIC), a programmable gatearray (PGA) including a Field PGA, or a state machine deployed on ahardware device, a computing device or any other hardware equivalents,e.g., computer readable instructions pertaining to the methods discussedabove can be used to configure a hardware processor to perform thesteps, functions and/or operations of the above disclosed method 300and/or method 400. In one example, instructions and data for the presentmodule or process 505 for selecting paths in ROADM networks usingmachine learning (e.g., a software program comprisingcomputer-executable instructions) can be loaded into memory 504 andexecuted by hardware processor element 502 to implement the steps,functions, or operations as discussed above in connection with theillustrative method 300 and/or method 400. Furthermore, when a hardwareprocessor executes instructions to perform “operations,” this couldinclude the hardware processor performing the operations directly and/orfacilitating, directing, or cooperating with another hardware device orcomponent (e.g., a co-processor and the like) to perform the operations.

The processor executing the computer readable or software instructionsrelating to the above described method(s) can be perceived as aprogrammed processor or a specialized processor. As such, the presentmodule 505 for selecting paths in ROADM networks using machine learning(including associated data structures) of the present disclosure can bestored on a tangible or physical (broadly non-transitory)computer-readable storage device or medium, e.g., volatile memory,non-volatile memory, ROM memory, RAM memory, magnetic or optical drive,device or diskette, and the like. Furthermore, a “tangible”computer-readable storage device or medium comprises a physical device,a hardware device, or a device that is discernible by the touch. Morespecifically, the computer-readable storage device may comprise anyphysical devices that provide the ability to store information such asdata and/or instructions to be accessed by a processor or a computingdevice such as a computer or an application server.

While various examples have been described above, it should beunderstood that they have been presented by way of illustration only,and not a limitation. Thus, the breadth and scope of any aspect of thepresent disclosure should not be limited by any of the above-describedexamples, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. A method comprising: defining, by a processingsystem including at least one processor, a feature set for a proposedpath through a wavelength division multiplexing network, wherein theproposed path traverses at least one link in the wavelength divisionmultiplexing network, and wherein the at least one link connects a pairof reconfigurable optical add/drop multiplexers; predicting, by theprocessing system, an optical performance of the proposed path, whereinthe predicting employs a machine learning model that takes the featureset as an input and outputs a metric that quantifies a predicted opticalperformance of the proposed path; and determining, by the processingsystem, whether to deploy a new wavelength on the proposed path based onthe predicted optical performance of the proposed path.
 2. The method ofclaim 1, wherein the machine learning model is a penalized linearregression model.
 3. The method of claim 1, wherein the machine learningmodel is an ensemble of regression trees.
 4. The method of claim 3,wherein the machine learning model is a random forest model.
 5. Themethod of claim 1, wherein the metric is a bit error rate of theproposed path.
 6. The method of claim 5, wherein the bit error rate is abit error rate before forward error correction.
 7. The method of claim6, wherein the bit error rate is a log₁₀(bit error rate).
 8. The methodof claim 1, wherein the determining comprises: determining the metricsatisfies an optical performance standard; and deploying the newwavelength on the proposed path.
 9. The method of claim 8, wherein theoptical performance standard is a threshold value for the metric. 10.The method of claim 8, further comprising: collecting data regarding anoptical performance of the proposed path, after the deploying.
 11. Themethod of claim 10, further comprising: training the machine learningmodel using the data.
 12. The method of claim 1, wherein the determiningcomprises: generating a new proposed path, when the metric fails tosatisfy an optical performance standard; defining a new feature set forthe new proposed path, wherein the new proposed path traverses at leastone link in the wavelength division multiplexing network, and whereinthe at least one link of the new proposed path connects a pair ofreconfigurable optical add/drop multiplexers; predicting an opticalperformance of the new proposed path using the machine learning model,wherein the machine learning model takes the new feature set as an inputand outputs a new metric that quantifies a predicted optical performanceof the new proposed path; and determining whether to deploy the newwavelength on the new proposed path based on the predicted opticalperformance of the new proposed path.
 13. The method of claim 1, furthercomprising: defining a feature set for an existing path, wherein theexisting path traverses at least one link in the wavelength divisionmultiplexing network, and wherein the at least one link of the existingpath connects a pair of reconfigurable optical add/drop multiplexers;predicting an optical performance of the existing path, wherein thepredicting employs the machine learning model, wherein the machinelearning model takes the feature set for the existing path as an inputand outputs a metric that quantifies a predicted optical performance ofthe existing path; and determining whether to move an existingwavelength from the existing path to an alternative path based on thepredicted optical performance of the existing path.
 14. A non-transitorycomputer-readable medium storing instructions which, when executed by aprocessing system including at least one processor, cause the processingsystem to perform operations, the operations comprising: defining afeature set for a proposed path through a wavelength divisionmultiplexing network, wherein the proposed path traverses at least onelink in the wavelength division multiplexing network, and wherein the atleast one link connects a pair of reconfigurable optical add/dropmultiplexers; predicting an optical performance of the proposed path,wherein the predicting employs a machine learning model that takes thefeature set as an input and outputs a metric that quantifies a predictedoptical performance of the proposed path; and determining whether todeploy a new wavelength on the proposed path based on the predictedoptical performance of the proposed path.
 15. A system comprising: aprocessor; and a non-transitory computer-readable medium storinginstructions which, when executed by the processor, cause the processorto perform operations, the operations comprising: defining a feature setfor a proposed path through a wavelength division multiplexing network,wherein the proposed path traverses at least one link in the wavelengthdivision multiplexing network, and wherein the at least one linkconnects a pair of reconfigurable optical add/drop multiplexers;predicting an optical performance of the proposed path, wherein thepredicting employs a machine learning model that takes the feature setas an input and outputs a metric that quantifies a predicted opticalperformance of the proposed path; and determining whether to deploy anew wavelength on the proposed path based on the predicted opticalperformance of the proposed path.
 16. The system of claim 15, whereinthe metric is a bit error rate of the proposed path.
 17. The system ofclaim 15, wherein the determining comprises: determining the metricsatisfies an optical performance standard; and deploying the newwavelength on the proposed path.
 18. The system of claim 17, theoperations further comprising: collecting data regarding an opticalperformance of the proposed path, after the deploying and training themachine learning model using the data.
 19. The system of claim 15,wherein the determining comprises: generating a new proposed path, whenthe metric fails to satisfy an optical performance standard; defining anew feature set for the new proposed path, wherein the new proposed pathtraverses at least one link in the wavelength division multiplexingnetwork, and wherein the at least one link of the new proposed pathconnects a pair of reconfigurable optical add/drop multiplexers;predicting an optical performance of the new proposed path using themachine learning model, wherein the machine learning model takes the newfeature set as an input and outputs a new metric that quantifies apredicted optical performance of the new proposed path; and determiningwhether to deploy the new wavelength on the new proposed path based onthe predicted optical performance of the new proposed path.
 20. Thesystem of claim 15, the operations further comprising: defining afeature set for an existing path, wherein the existing path traverses atleast one link in the wavelength division multiplexing network, andwherein the at least one link of the existing path connects a pair ofreconfigurable optical add/drop multiplexers; predicting an opticalperformance of the existing path, wherein the predicting employs themachine learning model, wherein the machine learning model takes thefeature set for the existing path as an input and outputs a metric thatquantifies a predicted optical performance of the existing path; anddetermining whether to move an existing wavelength from the existingpath to an alternative path based on the predicted optical performanceof the existing path.